Bermudagrass Johnsongrass Medusahead Quackgrass Field Bindweed Hoary Cress Diffuse Knapweed Russian Knapweed Spotted Knapweed Squarrose Knapweed Purple Loosestrife Perennial Pepperweed Leafy Spurge Yellow Starthsitle Canada Thistle Musk Thistle Scotch Thistle Dyer's Woad Back to main weeds page   Canada Thistle Cirsium arvense   Rosette Leaves have spiny tipped lobes. Adult Canada thistle is a perennial plant usually from one to four feet tall, in sparse to extremely dense colonies. Flower Flowerheads are softly spined, light pink to purple to white, and are typically three-quarter inch in diameter. Bloom occurs in July and August. Weed Infestation A native to southeastern Eurasia, Canada thistle reproduces by seeds and rootstock. It is adaptable to a diverse range of habitats. Seed Seed is attached to a soft parachute-like plume. Back to main weeds page   Buffalobur Common Burdock Camelthorn Goatsrue Jointed Goatgrass Poison Hemlock Black Henbane Houndstongue Blue-Flowering Lettuce Western Whorled Milkweed Silverleaf Nightshade Yellow Nutsedge Puncturevine Russian-Olive Saltcedar St. Johnswort Bull Thistle Dalmatian Toadflax Yellow Toadflax Velvetleaf